Struct ErasedReducePlan 

pub struct ErasedReducePlan { /* private fields */ }

Dtype-erased reduction wrapper.

This is the erased replay boundary for full-tensor scalar reductions and axis reductions with a fixed output layout. It supports only operations with an unambiguous identity value in the selected dtype.

Evaluation order

The op is matched once per execution; every loop runs a kernel specialized for one (dtype, op) pair. Integer results are exact (wrapping) and ReduceOp::Max / ReduceOp::Min do not depend on order, so the rules below only affect the rounding of floating point and complex ReduceOp::Sum, ReduceOp::Product and ReduceOp::SumSquares. Two details of float max and min follow the visit order: a NaN input makes the result NaN, but which NaN (payload and sign) is returned is unspecified, and when the extremum is a zero its sign is unspecified if both +0.0 and -0.0 occur.

• Full reductions (from Self::compile, or Self::compile_axes with every axis reduced) visit the source in a layout derived order: extent one axes are dropped, the rest are ordered by increasing absolute stride and contiguous axes are fused into runs. Each run is reduced by the SIMD kernel (unit stride, simd feature), a sixteen lane kernel (other unit stride runs) or an eight lane kernel (strided runs), and runs are combined left to right. A dense column major source therefore reduces exactly like one contiguous slice.
• With a parallel context and more than MINTHREADLENGTH elements, a full reduction splits the traversal into one deterministic range per worker thread. Each range runs the same run kernel as the serial path and the partials are combined in a fixed tree. The result is bitwise repeatable for a fixed layout and thread count, but may differ between thread counts and from the serial result.
• Axis reductions with kept axes compute every output independently, so the result never depends on the context or thread count. Each output folds its reduced elements sequentially in caller reduced axis order, except that a unit stride leading reduced run (after fusing adjacent reduced axes) of length at least 16 is reduced by the contiguous run kernel, with runs folded in order. When instead the leading kept axis has unit stride, adjacent outputs are accumulated as a block from one contiguous source run per reduced element; each output still folds in caller reduced axis order.

Implementations

impl ErasedReducePlan

pub fn compile( dtype: KernelDType, op: ReduceOp, dims: &[usize], src_strides: &[isize], ) -> Result<Self>

Validate and store a full-reduction plan for one dtype and source layout.

pub fn compile_axes( dtype: KernelDType, op: ReduceOp, src_dims: &[usize], src_strides: &[isize], dest_dims: &[usize], dest_strides: &[isize], axes: &[usize], ) -> Result<Self>

Validate and store an axis-reduction plan for one dtype and fixed source/output layouts.

axes names the source axes reduced away. Output dimensions must be the remaining source dimensions in source-axis order. When all axes are reduced, any output layout with exactly one reachable element is accepted.

pub fn dtype(&self) -> KernelDType

pub fn op(&self) -> ReduceOp

pub fn execute( &self, ctx: &ExecContext, dest: &mut ErasedRawStridedMut<'_>, src: &ErasedRawStridedRef<'_>, ) -> Result<()>

Execute the reduction into an erased output descriptor.

pub fn execute_uninit( &self, ctx: &ExecContext, dest: &mut ErasedRawStridedUninitMut<'_>, src: &ErasedRawStridedPtr<'_>, ) -> Result<()>

On success, every reachable destination slot is fully overwritten; unreachable holes are neither read nor initialized. Validation errors are returned before any destination write. A panic during execution may leave a partially initialized MaybeUninit destination, which is still safely droppable; no readable value is promised for unwritten reachable slots.

Trait Implementations

impl Clone for ErasedReducePlan

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ErasedReducePlan

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.